The foregoing insertion devices are known, for example, as insertion catheters and are used for placing a cardiac electrode line or a guide wire in the interior of the heart, in a coronary artery of the heart—such as the coronary sinus—or in a blood vessel connected adjoining the heart—such as the vena cava. Cardiac electrode lines are lines which produce an electrical contact between an electrically active implant such as a cardiac pacemaker or an implantable cardioverter/defibrillator (ICD) and an electrode head electrically connected to the heart, to stimulate the heart or record physiological measured values. Special embodiments of such electrodes, so-called “over the wire” electrodes, may be placed with the aid of a guide wire.
An insertion device of the type cited has a distal end, which faces toward the heart, and a proximal end, which is located outside the body and which is operated by the operator. A lumen section manufactured from a flexible plastic is located between the two ends, through whose lumen and the openings at the proximal and distal ends the cardiac electrode line or the guide wire is inserted. This lumen section has a diameter tailored to the thickness of the electrode line and/or the guide wire. After the insertion of the insertion device—if the distal end of the insertion device has been maneuvered to the desired point—an electrode line and/or a guide wire is inserted from the proximal end and then anchored on or in the heart by suitable fasteners.
A known problem of such insertion devices is that it is not possible to remove them simply by pulling them out, because the plug on the proximal end of the electrode line has a larger diameter than the lumen section of an insertion catheter due to standardized dimensions. Removal by shifting the insertion device in the proximal direction is thus not possible. This problem is solved according to the prior art in that the cited insertion devices may be slit or torn open from the proximal end to the distal end. It is thus made possible to remove the insertion device easily after placement of the electrode line. These insertion devices are often designed as directionally controllable, so that the placement is simplified. Such controllable and/or slittable insertion devices are described in EP 0 898 481, U.S. Pat. No. 6,159,198, and WO 99/33509.
In daily practice using such insertion devices, it has proven to be desirable to measure electrical signals such as electrical potentials or physiological signals during the insertion process of cardiac electrodes, to thus obtain a first impression of the physiological status of the fastening/stimulation location. Sometimes, it is also necessary to deliver stimulation pulses to thus find the optimum fastening/stimulation location of the electrode. This problem has been solved in insertion devices from the prior art in that at least one electrode is provided in the distal area, which may execute the cited functions. The measurement or stimulation pulses are generated by external stimulation threshold analyzers, for example. These units may record and/or process and analyze measured values from the heart. Such units are also used for delivering stimulation pulses and even for delivering defibrillation shocks in case of emergency.
WO 02/058785 discloses an insertion device having at least one electrode in the lumen section. The at least one electrode is manufactured from a metallic conductive material. A slittable or tearable insertion device is disclosed in U.S. Pat. No. 6,892,087, in which an electrode is situated on a dilator and the counter electrode is situated on the distal end of the insertion device. The at least one electrode is manufactured from metal, such as platinum or iridium or alloys thereof.
These two cited insertion devices from the prior art have the disadvantage, however, that the slitting and/or tearing open is possible not at all or only with great difficulty. The electrodes must additionally be thin-walled to keep the ratio of external diameter to lumen diameter of the lumen section small. Such an open, thin-walled metal electrode is very sharp-edged and may thus cause injuries during use.